Electronic timepiece

ABSTRACT

An electronic timepiece comprises power generation means for generating electricity by using external energy, storage means for storing electric energy received from the power generation means, time-indicating means powered by electric energy supplied from the power generation means or the storage means for indicating time, a switch circuit including a plurality of switching devices and adapted to transfer or intercept electric energy between the power generation means and the storage means and between the power generation means and the time-indicating means, voltage measuring means for measuring voltage across the time-indicating means, and control means that selects one of predetermined power ratios based on the results of measurement by the voltage measuring means and controls the switch circuit according to the selected ratio when the power generation means charges the storage means and the time-indicating means.

TECHNICAL FIELD

The present invention relates to an electronic timepiece (watch andclock) incorporating power generation means (generator) for generatingelectricity by utilizing external available energy, and particularly, toan electronic timepiece having a function of storing the electric energygenerated by the power generation means, and driving time-indicatingmeans for executing a time display operation by the agency of theelectric energy stored.

BACKGROUND TECHNOLOGY

There has lately become commercially practical an electronic timepieceprovided with built-in power generation means for converting externalenergy such as optical energy, thermal energy, mechanical energy, and soforth into electric energy, and utilizing the electric energy as drivingenergy for executing a time display operation.

Among such electronic timepieces provided with the built-in powergeneration means, there are included a solar cell timepiece using asolar cell, a mechanical electric power generation timepiece convertingmechanical energy generated by a rotary weight into electric energy andutilizing the same, and a thermoelectric power generation timepiecegenerating electricity by utilizing the difference in temperaturebetween the opposite ends of each of thermocouples connected in series.

It is essential for these electronic timepieces provided with thebuilt-in power generation means to have built-in means for storinggenerated electric energy therein while the external energy is availableso that the timepieces are driven continuously and stably all the timeeven when the external energy is no longer available. Such an electronictimepiece has been disclosed in, for example, JP, 4-81754, B.

FIG. 7 shows an example of a conventional electronic timepiece providedwith a built-in power generation means, including electric energystorage means.

With the timepiece, power generation means 10 is a solar cell, and thepositive terminal thereof is grounded, forming a closed circuit with afirst diode 43 and time-indicating means 21. The time-indicating means21 is comprised of a time-indicating block 22 for executing time displayby the agency of electric energy, and a capacitor 23 having capacitanceof 22 μF, which are connected in parallel.

Further, the power generation means 10 forms another closed circuit witha second diode 44, a first switching device 41, and storage means 30.

A second switching device 42 interconnects the negative terminal of thecapacitor 23 and the negative terminal of the storage means 30 such thatthe capacitor 23 and the storage means 30 can be coupled in parallel.

A switch circuit 40 for performing transfer or interruption of electricenergy among the power generation means 10, the storage means 30, andthe time-indicating means 21 is comprised of the first switching device41, the second switching device 42, the first diode 43, and the seconddiode 44.

Further, a first voltage comparator 16 compares a terminal voltage ofthe capacitor 23 with a first threshold value, and a second voltagecomparator 17 compares the terminal voltage of the capacitor 23 with asecond threshold value. The comparison result of the first voltagecomparator 16 and that of the second voltage comparator 17 are caused tobe inputted to a time-indicating block 22, thereby controlling the firstswitching device 41 by a first switching signal S21 outputted by acontrol circuit within the time-indicating block 22.

In this case, the first threshold value is −2.0 V, and the secondthreshold value is −1.5 V.

Further, a third voltage comparator 18 compares a terminal voltage ofthe storage means 30 with a third threshold value, and the comparisonresult thereof is caused to be inputted to the time-indicating block 22,thereby controlling the second switching device 42 by a second switchingsignal S22 outputted by the control circuit within the time-indicatingblock 22. In this case, the third threshold value is −2.0 V as well.

The first, second, and third voltage comparators 16, 17, 18 perform acomparison operation intermittently in a cycle of one second,respectively.

In a circuit diagram shown in FIG. 7, upon the start of generation ofelectric energy by the power generation means 10, the capacitor 23 ofsmall capacitance is first charged with the electric energy, and thetime-indicating means 21 starts a time-indicating operation by theagency of the electric energy stored in the capacitor 23. At this pointin time, the second switching device 42 is open.

Upon a voltage between the terminals of the capacitor 23 reaching 2.0 Vor higher, and an input voltage to the first voltage comparator 16becoming −2.0 V or lower since the positive terminal thereof isgrounded, the first voltage comparator 16 detects such a condition, anddepending on the result of detection, the time-indicating block 22closes the first switching device 41, thereby causing the storage means30 to be charged.

Conversely, upon a voltage between the terminals of the capacitor 23becoming lower than 1.5 V, and an input voltage to the second voltagecomparator 17 becoming higher than −1.5 V, the second voltage comparator17 detects such a condition, and depending on the result of detection,the time-indicating block 22 opens the first switching device 41,thereby causing the capacitor 23 side of the time-indicating means 21 tobe charged.

Further, upon a voltage between the terminals of the storage means 30exceeding 2.0 V as the charging of the storage means 30 proceeds, and aninput voltage to the third voltage comparator 18 becoming −2.0 V orlower, the third voltage comparator 18 detects such a condition, anddepending on the result of detection, the time-indicating block 22closes the second switching device 42, thereby causing both the storagemeans 30 and the capacitor 23 to be charged.

However, the electric energy generated by the power generation means 10undergoes variation depending on the external environment. For example,in the case of the solar cell, variation occurs mainly in quantity ofelectric current that can be outputted, and in the case of athermoelectric power generation device, a generated voltage undergoesvariation depending on the difference in temperature impressed fromoutside.

That is, depending on the external environment, the electric energygenerated by the power generation means 10 undergoes an abrupt increaseat times, thereby causing a voltage between the terminals of thecapacitor 23 inside the time-indicating means 21 to undergo an abruptrise.

As a result, there have occurred cases where an under-load drivingoperation of the time-indicating block 22 connected with the capacitor23 in parallel becomes unstable, so that time display can not beexecuted properly.

It is possible to solve this problem by various means such as byincreasing capacitance of the capacitor 23, by causing the respectivevoltage comparators to perform a comparison operation in a shortercycle, and so forth, however, a large capacitance capacitor results inan increase of the size thereof, so that such a capacitor can not beincorporated in a small-sized electronic timepiece such as a wristwatch.

Further, since an amplifier such as the first, second, and third voltagecomparators 16, 17, 18 has relatively large energy consumption, therehas also arisen a problem that frequent activation of the voltagecomparators deteriorates energy efficiency.

The invention has been developed to solve the above-described problemsencountered by the conventional electronic timepiece provided with thebuilt-in power generation means, and it is therefore an object of theinvention to enable control of the under-load driving operation for timedisplay and the charging of the storage means to be efficiently executedeven if variation occurs to a terminal voltage of the power generationmeans or to that of the storage means.

DISCLOSURE OF THE INVENTION

To this end, an electronic timepiece according to the inventioncomprises: power generation means for generating electricity fromexternal energy; storage means for storing the electric energy generatedby the power generation means; time-indicating means for executing timedisplay operation by use of the electric energy supplied from the powergeneration means or the storage means; a switching circuit comprising atleast a plurality of switching devices, for executing transfer orinterruption of the electric energy among the power generation means,the storage means, and the time-indicating means; voltage-measuringmeans for measuring a terminal voltage of the time-indicating means,being capable of deciding in which range the voltage is included amongat least three levels of voltage ranges; and control means forcontrolling the switching circuit by determining a ratio of electricenergy to be distributed between the storage means and thetime-indicating means in a set period during charging of the storagemeans and the time-indicating means by the power generation means at anyof at least three different ratios predetermined so that the ratioscorrespond to the voltage ranges one-to-one, according to results ofmeasurement by the voltage measuring means.

The control means can be constituted so as to control the switchingcircuit by determining a ratio of supply time of charge current from thepower generation means to the storage means to supply time of chargecurrent from the power generation means to the time-indicating means inthe set period during charging of the storage means and thetime-indicating means by the power generation means at any of at leastthree different ratios predetermined so that the ratios correspond tothe voltage ranges one-to-one, according to the voltage range decided bythe voltage measuring means.

Or the control means may be constituted so as to control the switchingcircuit by determining a ratio of impedance of a charge current supplycircuit from the power generation means to the storage means toimpedance of a charge current supply circuit from the power generationmeans to the time-indicating means during charging of the storage meansand the time-indicating means by the power generation means at any of atleast three predetermined different ratios according to the voltagerange decided by the voltage measuring means.

Further, the electronic timepiece according to the invention maycomprise: power generation means for generating electricity fromexternal energy; voltage-up means (booster means) for boosting a voltagegenerated by the power generation means; storage means for storingelectric energy boosted by the voltage-up means; time-indicating meansfor executing time display operation by use of the electric energysupplied from the voltage-up means or the storage means; a switchingcircuit comprising at least a plurality of switching devices, forexecuting transfer or interruption of the electric energy among thevoltage-up means, the storage means, and the time-indicating means;voltage-measuring means for measuring a terminal voltage of thetime-indicating means, being capable of deciding in which range thevoltage is included among at least three levels of voltage ranges; andcontrol means for controlling the switching circuit by determining aratio of electric energy to be distributed between the storage means andthe time-indicating means in a set period during charging of the storagemeans and the time-indicating means by the power generation means viathe voltage-up means at any of at least three different ratiospredetermined so that the ratios correspond to the voltage rangesone-to-one, according to results of measurement by the voltage measuringmeans.

In such a case as described above, the control means can be constitutedso as to control the switching circuit by determining a ratio of supplytime of charge current from the voltage-up means to the storage means tosupply time of charge current from the voltage-up means to thetime-indicating means in the set period during charging of the storagemeans and the time-indicating means by the power generation means viathe voltage-up means at any of at least three different ratiospredetermined so that the ratios correspond to the voltage rangesone-to-one, according to the voltage range decided by the voltagemeasuring means.

Or the control means may be constituted so as to control the switchingcircuit by determining a ratio of impedance of a charge current supplycircuit from the voltage-up means to the storage means to impedance of acharge current supply circuit from the voltage-up means to thetime-indicating means during charging of the storage means and thetime-indicating means by the power generation means at any of at leastthree predetermined different ratios according to the voltage rangedecided by the voltage measuring means.

Further, with either of the electronic timepieces as described above,the time-indicating means is preferably provided with electric energyamount control means for controlling an amount of electric energyconsumed by the time-indicating means for executing time display so asto be within a predetermined range all the time according to the resultsof measurement by the voltage measuring means.

Furthermore, in the case of the time-indicating means comprising astepping motor, the electric energy amount control means is preferablyconstituted so as to control an amount of electric energy consumed bythe time-indicating means for executing time display so as to be withina predetermined range all the time by setting a pulse at which electriccurrent is supplied to the stepping motor to any of a plurality ofpredetermined different shapes as selected according to the results ofmeasurement by the voltage measuring means.

With any of the electronic timepieces as described above, thetime-indicating means preferably comprises an auxiliary storage meansfor temporarily storing the electric energy.

With the electronic timepieces according to the invention constituted asdescribed above, the electric energy generated by the power generationmeans can be distributed between the time-indicating means and thestorage means at a suitable ratio of electric energy for charging theboth. This enables efficiency of charging the storage means with theelectric energy generated by the power generation means to be renderedbetter than before even if a cycle of the measurement is the same asbefore.

Further, even if an abrupt change occurs to the electric energygenerated due to a change in the external environment, it is possible toprevent an abrupt change from occurring to a voltage between theterminals of the time-indicating means, so that time-indicatingoperation of the time-indicating means can be stabilized.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block circuit diagram showing the constitution of a firstembodiment of an electronic timepiece according to the invention;

FIG. 2 is a circuit diagram showing a specific example of atime-indicating block, voltage-measuring means, and control means of theelectronic timepiece shown in FIG. 1;

FIG. 3 is a waveform chart showing a waveform in respective parts of theelectronic timepiece shown in FIGS. 1 and 2;

FIG. 4 is a block circuit diagram showing the constitution of a secondembodiment of an electronic timepiece according to the invention;

FIG. 5 is a block circuit diagram showing the constitution of a thirdembodiment of an electronic timepiece according to the invention;

FIG. 6 is a circuit diagram showing a specific example of control meansof the electronic timepiece shown in FIG. 5; and

FIG. 7 is a block circuit diagram showing an example of the constitutionof a conventional electronic timepiece provided with built-in powergeneration means.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of an electronic timepiece according to the invention willbe described in more detail hereinafter with reference to theaccompanying drawings.

First Embodiment

FIGS. 1 to 3

A first embodiment of an electronic timepiece according to the inventionis described referring to FIGS. 1 to 3.

FIG. 1 is a block circuit diagram showing the constitution of theelectronic timepiece, and in the figure, parts corresponding to those ofthe conventional example shown in FIG. 7 are denoted by like referencenumerals. FIG. 2 is a circuit diagram showing a specific example of atime-indicating block 25, voltage measuring means 80, and control means50, shown in FIG. 1, and FIG. 3 is a waveform chart showing a signalwaveform of respective parts of the electronic timepiece.

With this embodiment, it is assumed that use is made of a thermoelectricpower generator (thermoelectric device) for converting energy caused bythe difference in temperature existing outside of the electronictimepiece to electric energy as power generation means 10 incorporatedin the electronic timepiece. However, the scope of the invention is notlimited thereto, and a solar cell, a mechanical electric powergenerator, or so forth may be used instead.

Further, although not shown in the figure, the electronic timepieceaccording to this embodiment has a construction wherein thethermoelectric device comprised of a plurality of thermocouplesconnected in series, serving as the power generation means 10, isdisposed so as to cause a hot junction side thereof to be in contactwith a case back, and a cold junction side thereof to be in contact witha metal case thermally insulated from the case back cover so that theelectronic timepiece is driven by generated electric energy obtained bythe difference in temperature occurring between the metal case and thecase back when the electronic timepiece is being carried by a user.

In this case, the power generation means 10 is assumed to be able todevelop a thermoelectromotive force (voltage) of about 2.0 V for every1° C. of the difference in temperature occurring between the hotjunction side and the cold junction side.

As with the conventional example shown in FIG. 7, with the timepieceaccording to this embodiment as well, the power generation means 10 hasthe positive terminal that is grounded, forming a closed circuit with afirst diode 43 and time-indicating means 20.

The time-indicating means 20 is comprised of a time-indicating block 25for executing time display by the agency of electric energy, and acapacitor 23 having small capacitance of 22 μF, which are connected inparallel.

Further, the power generation means 10 forms another closed circuit witha second diode 44, a first switching device 41, and storage means 30.

A second switching device 42 interconnects the negative terminal of thecapacitor 23 and the negative terminal of the storage means 30 such thatthe capacitor 23 and the storage means 30 can be coupled in parallel.

A switching circuit 40 for executing transfer or interruption ofelectric energy among the power generation means 10, the storage means30, and the time-indicating means 20 is comprised of the first andsecond switching devices 41, 42 and the first and second diodes 43, 44.

The first diode 43 and the second diode 44, serving as switching devicesfor preventing backward flow of electric energy to the power generationmeans 10, are connected to the power generation means 10.

That is, the cathode of both the first diode 43 and the second diode 44is connected to the negative terminal of the power generation means 10.The anode of the first diode 43 is connected to the negative terminal ofthe time-indicating means 20 while the anode of the second diode 44 isconnected to the negative terminal of the storage means 30 via the firstswitching device 41. Accordingly, the drain terminal of the firstswitching device 41 is connected to the negative terminal of the storagemeans 30, and the source terminal of the first switching device 41 isconnected to the anode of the second diode 44.

The storage means 30 is, for example, a lithium ion secondary cell, andis provided in order to store electric energy generated by the powergeneration means 10 so as to enable the time-indicating means 20 to beoperational even when no power is being generated by the powergeneration means 10. The storage means 30 as well has the positiveterminal that is grounded.

The second switching device 42 is provided for the purpose of connectingthe storage means 30 and the time-indicating means 20 in parallel. Thatis, the drain terminal of the second switching device 42 is connected tothe negative terminal of the time-indicating means 20, and the sourceterminal thereof is connected to the negative terminal of the storagemeans 30.

The first switching device 41 and the second switching device 42 arecomprised of a MOS field effect transistor (FET), respectively, servingas a switching device for charging and discharging the storage means 30.

The time-indicating block 25 of the time-indicating means 20 compriseswave-generating means 51 for dividing the frequency of oscillatingsignals generated by a crystal oscillator used in common electronictimepieces and generating a driving waveform for a stepping motor 28,and a time display means 27 including the stepping motor 28, gears, thehands (the hour hand, the minute hand, the second hand) for displayingtime, and so forth driven by the driving waveform generated by thewave-generating means 51 (refer to FIG. 2). The constitution of thetime-indicating block 25 will be further described in detail later on.

As with common type electronic timepieces, a complementary field effectMOS (CMOS) integrated circuit is used for a control circuit part of thetime-indicating block 25 although not shown in the figure.

Further, the electronic timepiece according to this embodiment of theinvention is provided with the voltage measuring means 80 capable ofdetermining whether a voltage between the terminals of the capacitor 23is less than 1.2 V, in a range from 1.2 V to 1.6 V, or in excess of 1.6V, and also capable of determining whether a voltage between theterminals of the storage means 30 is less than 1.5 V or not less than1.5 V.

A voltage at the negative terminal of the capacitor 23, and a voltage atthe negative terminal of the storage means 30 are inputted to thevoltage measuring means 80, and an output therefrom, that is, a firstmeasurement result signal S81 to a third measurement result signal S83are inputted to the control means 50. The control means 50 receivessignals S1 to S4 from the time-indicating block 25, and outputs a firstswitch signal S41 and a second switch signal S42, thereby controllingopening and closing of the first and second switching devices 41, 42.Also, the control means 50 cause output signals S50 to S53 to beinputted to the time-indicating block 25.

Now, referring to FIG. 2, the time-indicating block 25, the voltagemeasuring means 80, and the control means 50 are described in detail.

As shown in FIG. 2, the voltage measuring means 80 according to thisembodiment is comprised of a first dividing resistor 81, a first dividerswitch 82, a first amplifier 85, a second amplifier 86, a seconddividing resistor 83, a second divider switch 84, a third amplifier 87,and a constant voltage circuit 88.

Further, the control means 50 is comprised of a first latch 54, a secondlatch 55, a third latch 56, and a fourth latch 53, a first AND gate 57,a second AND gate 58, and a third AND gate 59, and an OR gate 60.

The time-indicating block 25 of the time-indicating means 20 iscomprised of the wave-generating means 51, fourth to sixth AND gates 61,62, 63, a first NOR gate 64, a toggle flip-flop 65, second and third NORgates 66, 67, first and second drivers 68, 69, and the time displaymeans 27.

The logic gates described above are of a dual input type unlessspecified otherwise.

The wave-generating means 51 is a part of the time-indicating block 25,for dividing the frequency of the oscillating signal generated by thecrystal oscillator at least until the signal has an oscillating periodof 2 seconds or more, and further, transforming a divided signal into awaveform necessary for driving the stepping motor 28 incorporated in thetime display means 27 as with the case of the common type electronictimepieces.

Further, the time display means 27 is comprised of the stepping motor28, reduction gears (not shown), the hands for time display, a dial, andso froth, and is a part of the time-indicating block 25, fortransmitting rotation of the stepping motor 28 while reducing a rotationvelocity thereof by the agency of the reduction gears to thereby rotatethe hands for time display, thus executing time display.

Since the wave-generating means 51 and the time display means 27 aresimilar in constitution to those of the common type electronictimepieces, detailed description thereof is omitted.

The wave-generating means 51 outputs a measurement signal S1, first tothird distribution signals S2, S3, S4, and first to third displaysignals S5, S6, S7.

The measurement signal S1 is in a waveform rising to the HIGH level in60 μs, having a period of one second.

Further, the first to third distribution signals S2, S3. S4 are signalsproviding timing as a basis on which the electric energy generated bythe power generation means 10 is distributed between the storage means30 and the capacitor 23.

The first to third distribution signals S2, S3, S4 are all in a waveformhaving a period of one second, the first distribution signal S2 stays atthe HIGH level for a duration of 875 milliseconds, the seconddistribution signal S3 stays at the HIGH level for a duration of 750milliseconds, and the third distribution signal S4 stays at the HIGHlevel for a duration of 500 milliseconds.

The first to third display signals S5, S6, S7 are signals serving as abasis on which the stepping motor 28 incorporated in the time displaymeans 27 is rotatably driven.

The first to third display signals S5, S6, S7 are all in a waveformhaving a period of one second, the first display signal S5 stays at theHIGH level for a duration of 3 milliseconds, the second display signalS6 stays at the HIGH level for a duration of 3.5 milliseconds, and thethird display signal S7 stays at the HIGH level for a duration of 4milliseconds.

In this case, timing of a waveform rise of the measurement signal S1,and that of the first to third distribution signals S2, S3, S4,respectively, are all synchronized with each other while timing of awaveform rise of the first to third display signals S5, S6, S7,respectively, is synchronized with timing of a waveform fall of themeasurement signal S1.

Since generation of these waveforms can be implemented through a simplewaveform synthesis, description of a method of generating the waveformsis omitted.

The first to third amplifiers 85, 86, 87 within the voltage measuringmeans 80 are constituted in such a way as to be able to compare anoutput voltage of the constant voltage circuit 88 with the other inputvoltage of the respective amplifiers.

The constant voltage circuit 88 is a regulator circuit in common use forobtaining a constant voltage from a power source at a varying voltage.In this case, the constant voltage circuit 88 is to output a constantvoltage at −0.8 V, and is connected to the capacitor 23 such that energyfor driving the constant voltage circuit 88 is supplied from thecapacitor 23.

The capacitor 23 is a constituting element incorporated in thetime-indicating means 20 described hereinbefore.

The first dividing resistor 81 is a high-prevision high-resistanceelement, and one end of the first dividing resistor 81 is connected tothe drain terminal of the first divider switch 82 while the other end ofthe first dividing resistor 81 is rounded. The source terminal of thefirst divider switch 82 is connected to the negative terminal of thecapacitor 23.

Similarly, one end of the second dividing resistor 83 which is ahigh-precision high-resistance element is connected to the drainterminal of the second divider switch 84 while the other end of thesecond dividing resistor 83 is grounded. Further, the source terminal ofthe second divider switch 84 is connected to the negative terminal ofthe storage means 30.

With this embodiment, both the first dividing resistor 81 and the seconddividing resistor 83 have a resistance value of 600 KΩ, respectively.

The measurement signal S1 outputted from the time-indicating block 25 isinputted to the gate terminal of the first divider switch 82 as well asthe second divider switch 84.

The first to third amplifiers 85, 86, 87 are comparators for voltagedetection, and an output voltage of the constant voltage circuit 88 isinputted to a non-negative input terminal of the respective amplifiers.

Further, a midpoint of the first dividing resistor 81 is connected to anegative input terminal of the first amplifier 85. The midpoint islocated at a point having a resistance value (300 KΩ) as seen from theground side, equivalent to {fraction (2/4)} of the resistance value ofthe first dividing resistor 81.

Similarly, a point of the first dividing resistor 81, having aresistance value (400 KΩ from the ground side) equivalent to ⅔ of theresistance value of the first dividing resistor 81, is connected to anegative input terminal of the second amplifier 86.

Similarly further, a midpoint of the second dividing resistor 83 isconnected to a negative input terminal of the third amplifier 87. Such amidpoint is located at a point having a resistance value (320 KΩ) asseen from the ground side, equivalent to {fraction (8/15)} of theresistance value of the second dividing resistor 83.

With the constitution described above, upon turning the first dividerswitch 82 ON, flow of electric current occurs to the first dividingresistor 81, and {fraction (2/4)} of a negative terminal voltage of thecapacitor 23 is inputted to the first amplifier 85, whereupon if such aninput voltage falls below −0.8 V, that is, the output voltage of theconstant voltage circuit 88, the first amplifier 85 outputs the HIGHlevel, otherwise outputting the LOW level.

That is, it is set such that the output of the first amplifier 85 turnsto the HIGH level upon a voltage between the terminals of the capacitor23 exceeding 1.6 V.

Similarly, it is constituted such that the second amplifier 86 outputsthe HIGH level upon a voltage between the terminals of the capacitor 23exceeding 1.2 V, and the third amplifier 87 outputs the HIGH level upona voltage between the terminals of the storage means 30 exceeding 1.5V.

The first to third amplifiers 85, 86, 87 have an enable terminal,respectively, to which the measurement signal S1 is inputted. In otherwords, the first to third amplifiers 85, 86, 87 are operational onlywhen the measurement signal S1 is at the HIGH level.

Further, when the first to third amplifiers 85, 86, 87 are notoperational, that is, the enable terminal thereof is at the LOW level,an output of the respective amplifiers is to be raised to the HIGHlevel.

The output of the first amplifier 85, the second amplifier 86, and thethird amplifier 87, respectively, is inputted to a data input of thefirst latch 54, the second latch 55, and the third latch 56,respectively.

The output of the first amplifier 85 as the first measurement resultsignal S81, the output of the second amplifier 86 as the secondmeasurement result signal S82, and the output of the third amplifier 87as the third measurement result signal S83 is data input of the first tothird latches 54, 55, 56 of the control means 50 as described above,respectively.

The first to third latches 54, 55, 56 of the control means 50 are datalatches whose the output is reset when the power source is turned ON.The respective latches are provided with a clock terminal, to which themeasurement signal S1 is inputted, respectively, enabling retention andoutput of the signals with the data input at the falling edge of thewaveform of the measurement signal S1.

The first AND gate 57 outputs an AND of an output signal S50 of thefirst latch 54 and the first distribution signal S2. The second AND gate58 which is a triple-input AND gate outputs an AND of a negative outputsignal S51 of the first latch 54, an output signal S52 of the secondlatch 55, and the second distribution signal S3. Further, the third ANDgate 59 outputs an AND of a negative output signal S53 of the secondlatch 55, and the third distribution signal S4.

Further, the OR gate 60 is connected to the first AND gate 57, thesecond AND gate 58, and the third AND gate 59 so as to be able to outputan OR thereof. An output of the OR gate 60 is outputted as the firstswitch signal S41 to the switching circuit 40 in FIG. 1, therebycontrolling opening and closing of the first switching device 41.

Meanwhile, the output of the third latch 56 is data input to the fourthlatch 53. The fourth latch 53 as well is a data latch whose output isreset when the power source is turned ON. The third display signal S7 isinputted to the clock terminal of the fourth latch 53, enablingretention and output of the signal having data input at the falling edgeof the waveform of the third display signal S7.

Then, the output of the fourth latch 53 is outputted as the secondswitching signal S42 to the switching circuit 40 in FIG. 1, therebycontrolling opening and closing of the second switching device 42.

In the time-indicating block 25, the fourth AND gate 61 outputs an ANDof the output signal S50 of the first latch 54 and the first displaysignal S5. The fifth AND gate 62 which is a triple-input AND gateoutputs an AND of the negative output signal S51 of the first latch 54,the output signal S52 of the second latch 55, and the second displaysignal S6. Further, the sixth AND gate 63 outputs an AND of the negativeoutput signal S53 of the second latch 55 and the third display signalS7.

In addition, the first NOR gate 64 outputs a negative signal of an OR ofoutput of the fourth AND gate 61, the fifth AND gate 62, and the sixthAND gate 63. The output of the first NOR gate 64 is sent out as a selectdisplay signal S8.

The toggle flip-flop 65 is a toggle type flip-flop for inverting asignal to be retained and to be outputted every time an input signalrises, and the select display signal S8 is inputted thereto. For thesake of simplification in description, with the toggle flip-flop 65,retained data is assumed to be reset upon turning the power source ON inthis case.

Further, the second NOR gate 66 outputs a negative signal of an OR of anoutput of the toggle flip-flop 65 and the select display signal S8.

Similarly, the third NOR gate 67 outputs a negative signal of an OR of anegative output of the toggle flip-flop 65 and the select display signalS8.

An output of the second NOR gate 66 is inputted to the first driver 68,and an output of the third NOR gate 67 is inputted to the second driver69, so that the stepping motor 28 incorporated in the time display means27 interconnects an output of the first driver 68 and an output of thesecond driver 69.

The first driver 68 and the second driver 69 are inverters with a verylow impedance at the output terminal, respectively, and are constitutedsuch that electric current i22 in an optional direction can be suppliedto the stepping motor 28 connected to the respective output terminals byturning an input of either of the first driver 68 and the second driver69 to the HIGH level while turning an input of the other to the LOWlevel.

With this embodiment, the voltage measuring means 80, the control means50, and the time-indicating block 25 are constituted as described in theforegoing.

Now, operation of the electronic timepiece according to this embodimentis described with reference to FIGS. 1 and 2, and a waveform chart shownin FIG. 3.

First, the electronic timepiece is assumed to be in a condition whereinelectric energy stored in the storage means 30 has been nearly depletedwith a voltage between the terminals thereof at about 0.9V, and thetime-indicating means 20 is out of operation.

The electronic timepiece according to this embodiment is constitutedsuch that electronic timepiece in such a condition becomes operationalwhen the voltage between the terminals of the storage means 30 reaches1.0 V or higher, and such an actuation operation is first describedhereinafter.

With the electronic timepiece at rest as described above, the powergeneration means 10 starts generation of electric energy in the forwarddirection, upon a voltage generated reaching about 1.0 V, the firstdiode 43 is turned ON, and the electric energy generated by the powergeneration means 10 is supplied to the time-indicating means 20.

When the time-indicating means 20 is thereby actuated, thewave-generating means 51 within the time-indicating block 25, shown inFIG. 2, starts outputting the measurement signal S1, the first to thirddistribution signals S2 to S4, and the first to third display signals S5to S7, respectively.

Further, immediately after the actuation of the time-indicating means20, the first latch 54, the second latch 55, the third latch 56, and thefourth latch 53 are initialized such that any of the latches outputs theLOW level.

As a result, the third AND gate 59 inside the control means 50 outputsthe third distribution signal S4 as it is, while an output of the firstAND gate 57 and the second AND gate 58 are kept at the LOW level.Accordingly, the first switch signal S41 which is the output of the ORgate 60 is the same as the third distribution signal S4, therebycontrolling opening and closing of the first switching device 41.

Further, the second switch signal S42 remains at the LOW level, and thesecond switching device 42 controlled thereby is turned into an OFFcondition.

At this point in time, a negative signal of the third display signal S7appears in the select display signal S8 in the time-indicating block 25.However, as HIGH-level pulses of the measurement signal S1 appeartherein immediately thereafter, the electronic timepiece proceeds inpractice immediately to an operation taking place after the start ofpower generation as described hereinafter.

Upon appearance of the HIGH-level pulses in the measurement signal S1,both the first divider switch 82 and the second divider switch 84 of thevoltage measuring means 80 are turned ON while the measurement signal S1remains at the HIGH level, and subsequently, flow of electric currentoccurs to the first dividing resistor 81 and the second dividingresistor 83. As a result, a voltage equivalent to {fraction (2/4)} of avoltage between the terminals of the capacitor 23, and a voltageequivalent to ⅔ of a voltage between the terminals of the capacitor 23are inputted to the first amplifier 85, and the second amplifier 86,respectively. Similarly, a voltage equivalent to {fraction (8/15)} of avoltage between the terminals of the storage means 30 is inputted to thethird amplifier 87.

At the fall timing of the measurement signal S1, the first latch 54, thesecond latch 55, and the third latch 56 capture an output of the firstamplifier 85, the second amplifier 86, and the third amplifier 87,respectively.

Assuming that a storage voltage is low at 0.9 V but a generated voltageis sufficiently high at this point in time, and a voltage between theterminals of the capacitor 23 is in exceed of 1.6 V, both the firstamplifier 85 and the second amplifier 86 output the HIGH level, andconsequently, both the first latch 54 and the second latch 55 capturethe HIGH level, and send out the same.

Hereupon, an output of any of the second AND gate 58, the third AND gate59, the fifth AND gate 62, and the sixth AND gate 63 turns to the LOWlevel while either of inputs to the first AND gate 57 and the fourth ANDgate 61 turns to the HIGH level. As a result, the OR gate 60 outputs thefirst distribution signal S2 as it is, and the first NOR gate 64 outputsa negative signal of the first display signal S5.

Accordingly, at the falling edge of the measurement signal S1, the firstswitch signal S41 becomes the same as the first distribution signal S2,and the select display signal S8 becomes the same as the negative signalof the first display signal S5.

Since the toggle flip-flop 65 flips over an output thereof every time apulse at the LOW level is inputted, upon the select display signal S8becoming the same as the negative signal of the first display signal S5,it follows that the second NOR gate 66 and the third NOR gate 67alternately outputs a HIGH-level pulse of the first display signal S5.

This enables the first driver 68 and the second driver 69 to causeelectric current changing the direction of flow every one second insynchronization with the HIGH-level pulse of the first display signal S5to flow to the stepping motor 28. In FIGS. 2 and 3, the electric currentflowing to the stepping motor 28 is denoted by reference numeral i22.

The time display means 27 thereby executes rotation of the hands fortime display according to the first display signal S5 as with the caseof the common type electronic timepiece.

A this point in time, the first switch signal S41 is in the samewaveform as that of the first distribution signal S2, however, since anyof the first to third distribution signals S2 to S4 is at the HIGH levelin synchronization with the measurement signal S1, the first switchsignal S41 is at the HIGH level, thereby turning the first switchingdevice 41 into an ON condition.

Accordingly, the electric energy generated by the power generation means10 is delivered to the storage means 30, thereby charging the storagemeans 30.

Further, since the first distribution signal S2 at the HIGH level turnsto the LOW level after the elapse of 875 milliseconds from the risingedge of the measurement signal S1, the first switching device 41 isturned from an ON condition into an OFF condition, so that generatedelectric energy flowing from the power generation means 10 to thestorage means 30 is rerouted so as to flow to the side of thetime-indicating means 20, that is, to the capacitor 23.

At this point in time, the capacitor 23 is supplied with the generatedelectric energy for a short duration of 125 milliseconds (for every 1second), however, since a voltage between the terminals of the capacitor23 has already exceeded 1.6 V, there is no need for charging thecapacitor 23 to a large extent, so that no problem will arise even ifmost of the generated electric energy is used for charging the storagemeans 30.

Further, although electric current is supplied to the stepping motor 28incorporated in the time display means 27 for a duration of only 3milliseconds, a voltage between the terminals of the capacitor 23 issufficiently high, enabling sufficient driving electric current to besupplied to the stepping motor 28.

Subsequently, operation in the case where the generated electric energyof the power generation means 10 drops below the level described in theforegoing is described hereinafter.

Upon appearance of the HIGH-level pulse in the measurement signal S1,the first latch 54, the second latch 55, and the third latch 56 of thecontrol means 50 capture the output of the first amplifier 85, thesecond amplifier 86, and the third amplifier 87 of the voltage-measuringmeans 80, respectively, at the fall timing of the measurement signal S1.

At this point in time, assuming that the storage voltage is low at 0.9 Vbut a voltage between the terminals of the capacitor 23 is in the orderof 1.4 V due to a drop in the generated electric energy of the powergeneration means 10 and energy consumption caused by the time-indicatingmeans 20, the first amplifier 85 outputs the LOW level, and the secondamplifier 86 outputs the HIGH level. Accordingly, the first latch 54captures the LOW level, and the second latch 55 captures the HIGH level,respectively, before outputting the same.

Hereupon, as the OR gate 60 outputs the second distribution signal S3 asit is, and the first NOR gate 64 outputs a negative signal of the seconddisplay signal S6, the first switch signal S41 becomes the same as thesecond distribution signal S3, and the select display signal S8 becomesthe same as a negative signal of the second display signal S6 at thefalling edge of the measurement signal S1.

At this point in time, a voltage between the terminals of the capacitor23 is at around 1.4 V, lower than the previously described level,however, since electric current is supplied to the stepping motor 28 ofthe time-indicating block 25 for a duration of 3.5 milliseconds, longerthan the previously-described duration of 3 milliseconds, it is possibleto supply electric energy for driving the stepping motor 28substantially equivalent in quantity to that in the previously describedcase.

Further, the first switch signal S41 having turned to the HIGH level atthe rising edge of the measurement signal S1 will turn to the LOW levelwith the elapse of 750 milliseconds. It follows that the generatedelectric energy of the power generation means 10 will be delivered tothe capacitor 23 for a duration of 250 milliseconds.

In this case as well, since the generated electric energy of the powergeneration means 10 will be less than that for the previously describedcase, charging time of the capacitor 23 is rendered longer than 125milliseconds as for the previously described case, thereby enabling thetime-indicating block 25 to continue a time-indicating operation.

Further, when the previously-described condition of power generationcontinues, and a voltage between the terminals of the capacitor 23 islower than 1.2 V while a storage voltage is lower than 1.5 V, thetime-indicating means 20 sets the charging time of the capacitor 23 to500 milliseconds, and sets pulses for driving the stepping motor 28 at 4milliseconds by going through the same steps as described above.

Since electric energy stored in the capacitor 23 at this point in timeis lower than that in the previously described condition, the chargingtime of the capacitor 23 is rendered longer than 250 milliseconds as forthe previously described case, thereby enabling energy necessary forcontinuance of the time-indicating operation of the time-indicatingblock 25 to be obtained from the power generation means 10.

Further, as for the stepping motor 28 of the time-indicating block 25,energy necessary for driving the stepping motor 28 can be supplied tothe stepping motor 28 by setting time for supply of electric currentthereto longer than 3.5 milliseconds as set for the previously describedcase.

Operation in a condition wherein the charging of the storage means 30 issufficiently executed is described hereinafter.

In a condition wherein the charging of the storage means 30 proceeds,and a voltage between the terminals of the storage means 30 comes toexceed 1.5V, the output of the third amplifier 87 is the HIGH level whenthe third latch 56 of the control means 50 captures an output of thethird amplifier 87 of the voltage measuring means 80, and consequently,the third latch 56 captures the output, and outputs at the HIGH level.

The output of the third latch 56 is inputted to the fourth latch 53,however, this does not cause the second switch signal S42 to undergo animmediate change. At the falling edge of the third display signal S7,the fourth latch 53 captures the output of the third latch 56, therebycausing the second switch signal S42 to undergo a change to the HIGHlevel.

That is, the second switch signal S42 turns to the HIGH level at leastafter the select display signal S8 is turned to the LOW level.

Hereupon, the second switching device 42 shown in FIG. 1 is turned ON,and the time-indicating means 20 and the storage means 30 are connectedin parallel, so that electric energy generated by the power generationmeans 10 is supplied simultaneously to both the time-indicating means 20and the storage means 30.

By this point in time, a voltage between the terminals of the storagemeans 30 reaches a level sufficient for operation of the time-indicatingmeans 20, enabling the time-indicating means 20 to continue a stabletime-indicating operation thereafter.

With this embodiment, as a length of time for charging the capacitor 23is set so as to be half (500 milliseconds) of one second, that is, ameasuring cycle of the voltage measuring means 80, or less at most,variation in voltage between the terminals of the capacitor 23 can berendered more moderate than before even if the power generation means 10starts generation of power abruptly. As a result, the time-indicatingblock 25 can be stably operated.

Furthermore, with this embodiment, since it is arranged such that adriving condition of the stepping motor 28 incorporated in thetime-indicating block 25 is suitably set according to a voltage betweenthe terminals of the capacitor 23, even if a voltage between theterminals of the capacitor 23 rises slowly, electric energy within apredetermined range can be supplied to the stepping motor 28 accordingto such a condition, so that it is possible to drive the stepping motor28 efficiently.

Thus, with the first embodiment of the electronic timepiece according tothe invention, the control means 50 controls the switching circuit 40 bydetermining a ratio of electric energy to be distributed between thestorage means 30 and the time-indicating means 20 in a set period (1second in this example) during charging of the storage means 30 and thetime-indicating means 20 by the power generation means 10 at any of atleast three different ratios predetermined so that the ratios correspondto the voltage ranges one-to-one, according to results of measurement,that is, as described above, results of decision in which range thevoltage is included among at least three levels of voltage ranges, bythe voltage measuring means 80 for measuring a terminal voltage of thetime-indicating means 20 (a voltage between the terminals of thecapacitor 23).

The distribution ratio of the electric energy is varied by selecting anyof the first, second, and third distribution signals S2, S3, S4 shown inFIG. 3, having a different duty, respectively, as a first switch signal,and controlling the opening and closing of the first switching device 41by the signal, thereby selecting a ratio of supply time of chargecurrent from the power generation means 10 to the storage means 30 tothat of charge current from the power generation means 10 to thetime-indicating means 20.

In addition, with this embodiment, an amount of electric energy consumedby the time-indicating means 20 for executing time display is controlledby electric energy amount control means installed in the time-indicatingblock 25 so as to be within a predetermined range all the time on thebasis of the results of measurement by the voltage measuring means 80.

With this embodiment, the voltage measuring means 80 are put intocommission only once for every second for implementation of a chargingcontrol operation.

With the conventional electronic timepiece as shown in FIG. 7, voltagemeasurement needs to be performed at least 4 times for every second forimplementation of a similar charging control operation, and accordingly,with this embodiment, it is also possible to reduce measurement energynecessary for voltage measurement.

Further, with this embodiment, the thermoelectric power generator isemployed for the power generation means 10, however, other generatorsmay be employed. For example, a solar cell and the like may be employedfor the power generation means 10 without any problem.

Even in the case of employing the thermoelectric power generator for thepower generation means 10, use may be made of one having anelectromotive force of about 1.0 V for every 1° C. of the difference intemperature by reducing the number of the thermocouples composing thethermoelectric generator, utilizing a voltage-up circuit whereby agenerated voltage is boosted by a reduced portion thereof.

Second Embodiment

FIG. 4

Subsequently, a second embodiment of an electronic timepiece accordingto the invention, provided with power generation means and voltage-upmeans, is described hereinafter with reference to FIG. 4.

FIG. 4 is a block circuit diagram showing the constitution of theelectronic timepiece, and in the figure, parts corresponding to those inFIG. 1 are denoted by like reference numerals, description thereof isomitted.

The electronic timepiece according to this embodiment differs from theelectronic timepiece shown in FIG. 1 in that a voltage-up means 100 isinstalled and the constitution of a switching circuit 90 is somewhatdifferent from that of the switching circuit 40 shown in FIG. 1.

More specifically, with the electronic timepiece shown in FIG. 4, thevoltage-up means 100 which is a voltage-up circuit capable of boosting avoltage between the terminals of the power generation means 10 isconnected to the power generation means 10 in parallel. Further, a thirdswitching device 45 interconnects the negative terminal oftime-indicating means 20 and an output terminal of the voltage-up means100 while a fourth switching device 46 interconnects the negativeterminal of storage means 30 and the other output terminal of thevoltage-up means 100 such that an output of the voltage-up means 100 canbe apportioned between the time-indicating means 20 and the storagemeans 30.

Further, this embodiment is constituted such that the third switchingdevice 45 is controlled by a negative signal/S41, that is, the inverseof a first switch signal S41 outputted by an inverter 95, and the fourthswitching device 46 is controlled by the first switch signal S41, sothat the same operation and effect as those for the first embodimentdescribed in the foregoing can be obtained even in the case of utilizingthe voltage-up means.

In case that energy greater than normally required is needed for drivingthe stepping motor 28 shown in FIG. 2 or other loads, a ratio of timefor delivering electric energy generated by the power generation means10 to the time-indicating means 20 to the same for delivering electricenergy generated by the power generation means 10 to the storage means30 may be set at a value differing from that for the previouslydescribed case.

Third Embodiment

FIGS. 5 and 6

Next, a third embodiment of an electronic timepiece according to theinvention is described with reference to FIGS. 5 and 6. In thesefigures, parts corresponding to those in FIGS. 1 and 2 are denoted bylike reference numerals, and description thereof is omitted.

The electronic timepiece according to the third embodiment differs fromthe same according to the first embodiment shown in FIG. 1 only in thatcontrol means 70 and a switching circuit 110 differ from the controlmeans 50 and the switching circuit 40 as described previously,respectively.

In the switching circuit 110, a series circuit comprised of a switchingdevice Sa and a resistor R1, a series circuit comprised of a switchingdevice Sb and a resistor R2, and a series circuit comprised of aswitching device Sc and a resistor R3 are connected in parallel in placeof the first switching device 41 for interconnection between the anodeof a second diode 44, and the negative terminal of storage means 30.Further, a resistor R0 is interposed between a first diode 43 andtime-indicating means 20.

As shown in FIG. 6, the control means 70 is comprised of the same fourlatches as the first to fourth latches 54, 55, 56, 53 of the controlmeans 50 according to the first embodiment, and an AND gate 71 foroutputting an AND of the inverse of an output of the first latch 54 andan output of the second latch 55.

Then, the control means 70 sends out the output of the first latch 54 asa switch control signal Sa, an output of the AND gate 71 as a switchcontrol signal Sb, and the inverse of the output of the second latch 55as a switch control signal Sc to the switching circuit 110 in FIG. 5,thereby turning selectively any one of the switching device 41 a, theswitching device 41 b, and the switching device 41 c ON.

Thus, it follows that the resistor R0 remains interposed all the time ina charging circuit from power generation means 10 to the time-indicatingmeans 20 while any of the resistors R1, R2, and R3 is selectivelyinterposed in a charging circuit from the power generation means 10 tothe storage means 30.

Accordingly, the electronic timepiece according to the third embodimentis constituted such that the control means 70 determines a ratio ofimpedance of a charge current supply circuit from the power generationmeans 10 to the storage means 30 to the same from the power generationmeans 10 to the time-indicating means 20 at any of a plurality ofpredetermined different ratios (determined depending on a ratio of aresistance value of the resistor R0 to a resistance value of therespective resistors R1, R2, R3) according to results of measurement byvoltage-measuring means 80, thereby differentiating a ratio of electricenergy distributed between the storage means 30 and the time-indicatingmeans 20 by controlling the switching circuit 110.

Still, the same operation and effect as those for the electronictimepiece according to the first embodiment can be obtained.

By way of example, the resistance value of the resistors R0, R1, R2, andR3 are as follows:

R 0=100 Ω, R1=100 Ω, R2=150 Ω, and R3=175 Ω

By inputting the switch control signals Sa, Sb and Sc from the controlmeans 70 to a time-indicating block 25, an amount of electric energyconsumed by the time-indicating means 20 for executing time display iscontrolled by electric energy amount control means installed in thetime-indicating block 25 so as to be within a predetermined range allthe time on the basis of the results of measurement by the voltagemeasuring means 80 as with the case of the first embodiment.

Further, the electronic timepiece according to the second embodiment asshown in FIG. 4 can also be modified so as to have the same controlmeans as the control means 70 according to the third embodiment and thesame switching circuit as the switching circuit 110 according to thethird embodiment.

INDUSTRIAL UTILIZATION

As is evident from the foregoing description, the electronic timepieceaccording to the invention is constituted such that a voltage betweenthe terminals of the time-indicating means is measured, and a ratio ofelectric energy to be distributed when delivering the electric energygenerated by the power generation means to the side of thetime-indicating means, and to the side of the storage means can beoptimally set according to the results of the measurement.

This enables the electric energy generated to be adequately distributedbetween the time-indicating means and the storage means, and efficiencyof charging the storage means with the electric energy generated to berendered better than before even if a cycle of the measurement is thesame as before.

Further, even if an abrupt change occurs to the electric energygenerated due to a change in the external environment, it is possible toprevent an abrupt change from occurring to a voltage between theterminals of the time-indicating means, so that time-indicatingoperation of the time-indicating means can be stabilized.

Thus, the performance of the electronic timepiece provided with thepower generation means incorporated therein can be greatly enhanced.

What is claimed is:
 1. An electronic timepiece comprising: powergeneration means for generating electricity from external energy;storage means for storing the electric energy generated by said powergeneration means; time-indicating means for executing time displayoperation by use of the electric energy supplied from said powergeneration means or said storage means; a switching circuit comprisingat least a plurality of switching devices, for executing transfer orinterruption of the electric energy among said power generation means,said storage means, and said time-indicating means; voltage-measuringmeans for measuring a terminal voltage of said time-indicating means,being capable of deciding in which range the voltage is included amongat least three levels of voltage ranges; and control means forcontrolling said switching circuit by determining a ratio of electricenergy to be distributed between said storage means and saidtime-indicating means in a set period during charging of said storagemeans and said time-indicating means by said power generation means atany of at least three different ratios predetermined so that said ratioscorrespond to said at least three levels of voltage ranges one-to-one,according to a voltage range decided by said voltage-measuring means. 2.An electronic timepiece according to claim 1, wherein said control meansis means for controlling said switching circuit by determining a ratioof supply time of charge current from said power generation means tosaid storage means to supply time of charge current from said powergeneration means to said time-indicating means in a set period duringcharging of said storage means and said time-indicating means by saidpower generation means at any of the at least three different ratiospredetermined so that said ratios correspond to said at least threelevels of voltage ranges one-to-one, according to the voltage rangedecided by said voltage-measuring means.
 3. An electronic timepieceaccording to claim 1, wherein said control means is means forcontrolling said switching circuit by determining a ratio of impedanceof a charge current supply circuit from said power generation means tosaid storage means to impedance of a charge current supply circuit fromsaid power generation means to said time-indicating means duringcharging of said,storage means and said time-indicating means by saidpower generation means at any of the at least three different ratiospredetermined according to the at least three levels of voltage rangedecided by said voltage-measuring means.
 4. An electronic timepieceaccording to claim 1, wherein said time-indicating means is providedwith an electric energy amount control means for controlling an amountof electric energy consumed by said time-indicating means for executinga time display so as to be within a predetermined range all the timeaccording to the results of measurement by said voltage-measuring means.5. An electronic timepiece according to claim 4, wherein saidtime-indicating means comprises a stepping motor, and said electricenergy amount control means is means for controlling an amount ofelectric energy consumed for executing said time display so as to bewithin a predetermined range all the time by setting a pulse at whichelectric current is supplied to said stepping motor to any of aplurality of predetermined different shapes, as selected according tothe results of measurement by said voltage-measuring means.
 6. Anelectronic timepiece according to claim 1, wherein said time-indicatingmeans comprises an auxiliary storage means for temporarily storing theelectric energy.
 7. An electronic timepiece comprising: power generationmeans for generating electricity from external energy; voltage-up meansfor boosting a voltage generated by said power generation means; storagemeans for storing electric energy boosted by said voltage-up means;time-indicating means for executing time display operation by use of theelectric energy supplied from said voltage-up means or said storagemeans; a switching circuit comprising at least a plurality of switchingdevices for executing transfer or interruption of the electric energyamong said voltage-up means, said storage means, and saidtime-indicating means; voltage-measuring means for measuring a terminalvoltage of said time-indicating means, being capable of deciding inwhich range the voltage is included among at least three levels ofvoltage ranges; and control means for controlling said switching circuitby determining a ratio of electric energy to be distributed between saidstorage means and said time-indicating means in a set period duringcharging of said storage means and said time-indicating means by saidpower generation means via said voltage-up means at any of at leastthree different ratios predetermined so that said ratios correspond tosaid at least three levels of voltage ranges one-to-one, according to avoltage range decided by said voltage-measuring means.
 8. An electronictimepiece according to claim 7, wherein said control means is means forcontrolling said switching circuit by determining a ratio of supply timeof charge current from said voltage-up means to said storage means tosupply time of charge current from said voltage-up means to saidtime-indicating means in a set period during charging of said storagemeans and said time-indicating means by said power generation means viasaid voltage-up means at any of the at least three different ratiospredetermined so that said ratios correspond to said at least threelevels of voltage ranges one-to-one, according to the voltage rangedecided by said voltage-measuring means.
 9. An electronic timepieceaccording to claim 7, wherein said control means is means forcontrolling said switching circuit by determining a ratio of impedanceof a charge current supply circuit from said voltage-up means to saidstorage means to impedance of a charge current supply circuit from saidvoltage-up means to said time-indicating means during charging of saidstorage means and said time-indicating means by said power generationmeans at any of the at least three different ratios predeterminedaccording to the at least three levels of voltage range decided by saidvoltage-measuring means.
 10. An electronic timepiece according to claim7, wherein said time-indicating means is provided with an electricenergy amount control means for controlling an amount of electric energyconsumed by said time-indicating means for executing a time display soas to be within a predetermined range all the time according to theresults of measurement by said voltage-measuring means.
 11. Anelectronic timepiece according to claim 10, wherein said time-indicatingmeans comprises a stepping motor, and said electric energy amountcontrol means is means for controlling an amount of electric energyconsumed for executing said time display so as to be within apredetermined range all the time by setting a pulse at which electriccurrent is supplied to said stepping motor to any of a plurality ofpredetermined different shapes, as selected according to the results ofmeasurement by said voltage-measuring means.
 12. An electronic timepieceaccording to claim 7, wherein said time-indicating means comprises anauxiliary storage means for temporarily storing the electric energy.